Hydraulic cement compositions are often used in applications that are or will be associated with a relatively high level of carbon dioxide. For example, hydraulic cement compositions are used to encase the well bores of injection and production wells used in connection with enhanced oil recovery techniques. A fluid commonly used to flood the formation in such techniques is carbon dioxide. Specifically, the carbon dioxide is injected into the formation together with water through one or more injection wells to drive hydrocarbons in the formation toward one or more production wells. This technique has proved to be effective in increasing production of the hydrocarbons from the formation.
Hydraulic cement compositions are also used in other applications that involve or may involve a carbon dioxide environment. Examples include formation sealing applications and other cementing applications associated with oil, gas, water and geothermal wells and carbon capsule storage applications associated with power plants.
A problem that can result from the use of hydraulic cement compositions in applications that are or will be associated with a carbon dioxide environment is corrosion of the hydraulic cement by carbonic acid and other corrosive compounds formed by reactions between the carbon dioxide, water and potentially other compounds in the environment. Carbonic acid and other corrosive compounds formed from carbon dioxide can react with and penetrate into hardened hydraulic cement thereby lowering the compressive strength thereof. For example, carbonic acid corrosion can cause the production casing of an oil and gas well to fail resulting in undesired migration of fluids between the formation and well bore and other serious problems. Similar problems and adverse consequences can occur in other applications in which hydraulic cement compositions are used in carbon dioxide environments.
There is a need for a hydraulic cement composition that is resistant to corrosion by carbonic acid in downhole and other environments and that can be used in effective and efficient manners.